2012 TC4
![]() Radar movie of 2012 TC4[1] | |
Discovery[2][3] | |
---|---|
Discovered by | Pan-STARRS 1 |
Discovery site | Haleakala Obs. |
Discovery date | 4 October 2012 |
Designations | |
2012 TC4 | |
Orbital characteristics[2] | |
Epoch 1 October 2017 (JD 2458027.5) | |
Uncertainty parameter 1 | |
Observation arc | 5.19 yr (1,897 d) |
Aphelion | 1.8786 |
Perihelion | 0.9335 |
1.4061 | |
Eccentricity | 0.3361 |
1.67 yr (609 d) | |
332.79° | |
0° 35m 27.96s / day | |
Inclination | 0.8572° |
198.23° | |
222.58° | |
Earth MOID | 0.000149 |
Mars MOID | 0.03 |
Physical characteristics | |
Dimensions | 15 m × 8 m[5][6] |
7–13 m[7][8] 15 m[8] | |
| |
12.9–31[10] | |
2012 TC4 is a tumbling micro-asteroid classified as a bright near-Earth object of the Apollo group, approximately 10 meters (30 feet) in diameter.[6][7][8] It was first observed by Pan-STARRS at Haleakala Observatory on the Hawaiian island of Maui, in the United States. As of 1 October 2017, it had a small Earth minimum orbital intersection distance of 0.000149
Approaches to large bodies
[edit]Orbital modeling shows the asteroid nominally passed about 1 million km from Earth in October 1986, but the uncertainty region suggests it could have passed as close as 20 km.[2]
Date (UT) | Object | distance in km (center–center) |
3- uncertainty in km |
Speed- relative in km/s |
---|---|---|---|---|
13 October 1996 | Earth | 753 000 | ± 7000 | 6.445 |
13 October 1996 | Moon | 530 000 | ± 6300 | 7.144 |
12 October 2012 | Earth | 94 965 | ± 0.32 | 7.123 |
12 October 2012 | Moon | 113 886 | ± 0.64 | 6.773 |
12 October 2017 – 05:42 | Earth | 50 151 | ± 0.14 | 7.647 |
12 October 2017 – 19:19 | Moon | 277 697 | ± 0.34 | 6.101 |
Data from JPL 60 solution date 3 November 2017[2]
2012 Earth encounter
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/6/67/2012_TC4_observed_%28annotated%29.jpg/220px-2012_TC4_observed_%28annotated%29.jpg)
2012 TC4 was discovered on 4 October 2012 at apparent i-band magnitude 20.1 while the asteroid was 0.03
During the 2012 close approach, the asteroid only had an observation arc of 7 days, between 4 and 11 October 2012, so the exact distance of the 2017 closest approach was poorly constrained. With the 7 day observation arc, the asteroid had a 3-sigma chance of passing between 0.00008818 and 0.002896
2017 Earth encounter
[edit]On 12 October 2017 at 5:42 UT, the asteroid passed 0.00033524
Paul Chodas of NASA's Center for near-Earth Object Studies, and Vishnu Reddy of the University of Arizona's Lunar and Planetary Laboratory, viewed the 2017 flyby (inside of the orbit of the Moon) as a way to test and refine the global asteroid detection and tracking network designed to give warning of objects heading toward Earth.[16] Reddy coordinated the effort, involving over a dozen institutions worldwide.[16][18][19] In addition to the observation campaign, NASA used this exercise to test communications between the many observers and also to test internal U.S. government messaging and communications up through the executive branch and across government agencies, as it would during an actual predicted impact emergency. Results of the campaign were published on 3 November 2017.[5]
The asteroid remained too faint to be recovered with automated astronomical surveys until early September,[20] but a more targeted observation with the Very Large Telescope recovered it on 27 July 2017 at apparent magnitude 26.8, while the asteroid was 0.4
2012 TC4 reached a maximum apparent magnitude of 12.9 just prior to its closest approach, soon after which it came too close to the Sun to be seen with telescopes.[23] It was last observed on 14 December 2017 at an apparent magnitude of 25,[4]
Physical properties
[edit]![]() Size reference of 2012 TC4, based on radar observations. |
Fast rotator and tumbler
[edit]Studies of the asteroid's light curve in October 2012, found it to have a rotation period of 0.2038 hours (or 12 minutes and 14 seconds) with a brightness variation of 0.93 magnitude (U=3-), which is indicative for a non-spherical shape.[9][a] 2012 TC4 is a fast rotator, which is rather typical for its small size. The fastest rotator currently known is 2014 RC, a similarly sized NEO, with a period of only 16 seconds. Lightcurves obtained during the 2017 encounter confirmed that 2012 TC4 is in a non-principal axis rotation, commonly known as tumbling.[7][5] The spin axis varies on timescales of minutes, with a second period of 0.142 hours (or 8.5 minutes).[8] The lightcurve amplitude suggests a ratio of largest to smallest axis of at least 2.3.[7]
Radar observations
[edit]Radar images were taken from Goldstone Observatory and Green Bank Telescope on 12 October 2017. The delay-doppler images had a range resolution of 1.9 meters/pixel, the highest resolution ever obtained using Goldstone transmissions.[6][1] The images showed that 2012 TC4 was a very elongated object about 50 feet (15 meters) long and roughly 25 feet (8 meters) wide.[5] The high circular polarization ratio found for 2012 TC4 is consistent with results seen from E- and V-type NEAs previously.[6] Observations from Arecibo Observatory were planned, but had to be cancelled due to damage to the observatory as a result of Hurricane Maria.[25]
Composition
[edit]The spectrum of 2012 TC4 is that of an E- or Xe-type asteroid.[7][6] E-type asteroids tend to have a high albedo (>0.30). This agrees with the albedo of 0.35 found for 2012 TC4.[1] This type of asteroids is commonly found in the inner Main Belt.[26]
2012 TC4 is composed of igneous material.[5] The short rotation period of 2012 TC4 implies that it is not a rubble pile but rather a monolithic object of non-negligible strength, which is typical for very small asteroids.[7]
Orbit change
[edit]As a result of 2012 TC4's frequent approaches to Earth, its orbit changes significantly over short periods of only decades. Its two observed close approaches and their effects are shown below:
Date | Event | Semimajor axis ( |
Perihelion ( |
Aphelion ( |
Eccentricity | Inclination (°) | Argument of perihelion (°) | Ascending node (°) |
---|---|---|---|---|---|---|---|---|
2012-10-01 | pre-2012 approach | 1.2744 | 0.9015 | 1.6472 | 0.2926 | 1.4097 | 234.7282 | 198.5560 |
2012-10-12 | 2012 approach | 1.3837 | 0.9115 | 1.8559 | 0.3413 | 1.2320 | 228.5354 | 198.4622 |
2012-10-30 | post-2012 approach | 1.3893 | 0.9305 | 1.8480 | 0.3302 | 0.8582 | 223.1271 | 198.1033 |
2017-10-01 | pre-2017 approach | 1.4155 | 0.9410 | 1.8901 | 0.3353 | 0.8566 | 221.8553 | 198.0054 |
2017-10-12 | 2017 approach | 1.7076 | 0.9522 | 2.4630 | 0.4424 | 0.1693 | 218.4570 | 193.6520 |
2017-10-30 | post-2017 approach | 1.6492 | 0.9711 | 2.3273 | 0.4112 | 0.5327 | 248.6359 | 208.5051 |
2050-01-01 | pre-2050 approach | 1.6226 | 0.9688 | 2.2765 | 0.4030 | 0.5266 | 266.6192 | 197.8009 |
Between 2012 and 2017, 2012 TC4's average distance from the Sun increased by almost 0.4
As a result of non-gravitational forces such as the Yarkovsky effect on small bodies, it is difficult to constrain its orbit more than a few decades into the past or future.
See also
[edit]- List of asteroid close approaches to Earth
- List of asteroid close approaches to Earth in 2012
- List of asteroid close approaches to Earth in 2017
- NASA Planetary Defense Coordination Office
Notes
[edit]- ^ a b Lightcurve plot of 2012 TC4 at the Palmer Divide Observatory by Brian D. Warner (2012). Rotation period 0.2038±0.0002 hours with a brightness amplitude of 0.93±0.05 mag. Summary figures for 2012 TC4 at the LCDB
References
[edit]- ^ a b c "The 2012 TC4 Observing Campaign -- Radar animations". University of Maryland. Archived from the original on 7 November 2017. Retrieved 2 November 2017.
- ^ a b c d e f g h i j k l m n "JPL Small-Body Database Browser: (2012 TC4)" (2017-12-14 last obs.). Jet Propulsion Laboratory. Archived from the original on 28 November 2020. Retrieved 17 October 2017.
- ^ a b "MPEC 2012-T18 : 2012 TC4". IAU Minor Planet Center. 7 October 2012. Retrieved 14 March 2017. (K12T04C)
- ^ a b c d "2012 TC4". Minor Planet Center. Retrieved 4 November 2017.
- ^ a b c d e "Astronomers Complete First International Asteroid Tracking Exercise". JPL. 3 November 2017. Retrieved 3 November 2017.
- ^ a b c d e f "The 2012 TC4 Observing Campaign – Radar observations UPDATE October 12, 2017". University of Maryland. Retrieved 2 November 2017.
- ^ a b c d e f g h i Ryan, William H.; Ryan, Eileen V. (2017). "Physical Characterization of NEA 2012 TC4" (PDF) (PDF). University of Maryland. Retrieved 8 March 2018.
- ^ a b c d e f "NEA 2012 TC4 -- Physical Properties". University of Maryland. Retrieved 2 November 2017.
- ^ a b c d "LCDB Data for 2012 TC4". Asteroid Lightcurve Database (LCDB). Retrieved 28 September 2017.
- ^ a b "NEODyS-2 2012TC4". Department of Mathematics, University of Pisa, Italy. Retrieved 4 November 2017.
- ^ a b "Date/Time Removed". NASA/JPL Near-Earth Object Program Office. Archived from the original on 17 October 2017. Retrieved 17 October 2017.
- ^ a b "Archive: Earth Impact Risk Summary: 2012 TC4 (7 day observation arc)". NASA/JPL Near-Earth Object Program Office. Archived from the original on 24 November 2012. Retrieved 13 March 2017.
- ^ "Horizons Batch for 2022-10-12". JPL Horizons. Retrieved 4 October 2022.
- ^ "A Very Close Encounter". www.eso.org. Retrieved 11 August 2017.
- ^ a b "Archive: Close Approach table for 2012 TC4 (using 7 day obs arc)". JPL. NASA. Archived from the original on 3 April 2013. Retrieved 22 October 2014.
- ^ a b c "Asteroid Flyby Will Benefit NASA Detection and Tracking Network". JPL. NASA. 28 July 2017. Retrieved 8 March 2018.
- ^ "TC4: HOW NASA PLANS TO TEST ITS PLANETARY DEFENSE SYSTEMS ON CLOSE-APPROACH ASTEROID". Newsweek. 6 October 2017. Retrieved 7 October 2017.
- ^ Coleman, Nancy (1 August 2017). "NASA's planetary defense system will be put to the test in October". CNN. Retrieved 2 August 2017.
- ^ "The 2012 TC4 Observing Campaign". University of Maryland. Retrieved 2 November 2017.
- ^ "NEODyS-2 Possible recovery list". Department of Mathematics, University of Pisa, Italy. Archived from the original on 14 March 2017. Retrieved 14 March 2017.
- ^ "MPEC 2017-P26 : 2012 TC4". IAU Minor Planet Center. 6 August 2017. Retrieved 6 August 2017. (K12T04C)
- ^ Math:
- ^ a b "2012TC4 Ephemerides for 12 October 2017". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 7 August 2017.
- ^ "Orbit of NEA 2012 TC4". University of Maryland. Retrieved 11 October 2017.
- ^ "Goldstone Radar Observations Planning: 2012 TC4". JPL. Retrieved 2 November 2017.
- ^ Fornasier, S.; Clark, B. E.; Dotto, E. (July 2011). "Spectroscopic survey of X-type asteroids". Icarus. 214 (1): 131–146. arXiv:1105.3380. Bibcode:2011Icar..214..131F. doi:10.1016/j.icarus.2011.04.022. S2CID 118549118.
External links
[edit]- Interesting Asteroids Past Earth Close encounters — Sormano Astronomical Observatory
- Image and animation of 2012 TC4 – Virtual Telescope Project
- Asteroid 2012 TC4 On Track For Close Earth Flyby AstroBob 10/3/17
- Asteroid 2012 TC4: House-Sized Asteroid Almost Hits Earth (PHOTO, VIDEO) 13 October 2012
- 2012 TC4 orbit and observations, Minor Planet Center
- 2012 TC4 at NeoDyS-2, Near Earth Objects—Dynamic Site
- 2012 TC4 at ESA–space situational awareness
- 2012 TC4 at the JPL Small-Body Database